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Quercus infectoria Galls May Provide a Multitude of Medicinal Benefits

Date 08-31-2021
HC# 072111-671
Keywords:
Gall Oak (Quercus infectoria, Fagaceae)
Quercus infectoria galls (Galla Turcica)
Gallic Acid

Elham A, Arken M, Kalimanjan G, Arkin A, Iminjan M. A review of the phytochemical, pharmacological, pharmacokinetic, and toxicological evaluation of Quercus infectoria galls. J Ethnopharmacol. June 12, 2021;273:113592. doi: 10.106/j.jep.2020.113592.

Traditional medicine is derived from natural products primarily from plants but also from animals, minerals, and their processed products. The gall oak (Quercus infectoria, Fabaceae) is susceptible to galls produced by the gall wasp (Cynips gallae tinctoriae, Cynipideae). Gall oak galls (QIG; Galla turcica) have been used in traditional medicine to treat diarrhea, hemorrhage, and skin disease. Some studies have shown it to be an effective anti-MRSA, antiviral, antifungal, larvicidal, and antioxidant. Its powdered form has been used as a remedy for inflamed tonsils, skin edema, hemorrhoids, and inflammation. The purpose of this review was to compile a contemporary and comprehensive analysis of the medicinal uses and properties of QIG. Literature was compiled in both English and Chinese; details of the literature search were not included.

Formed by gall wasp larva, QIG are 1-2.5 cm in diameter, with a 2-3 mm wall and an earthy yellow verrucous appearance. They contain flavonoids, alkaloids, sterols, polyphenols, tannins, volatile oils, saponins, glycosides, sugars, organic acids, anthraquinones, proteins, and amino acids. Tannins comprise 50-70%. Gallic acid (GA) is the main phenolic acid (2-4%). Four triterpenoids and three steroids have been identified in QIG, along with several minerals. Only two flavonoids, amentoflavone and isocryptomerin, have been reported; consequently, flavonoids in QIG have not been studied.

Spectral analysis of QIG aqueous solutions found that the molecular structure is unaffected by ultrafine grinding before and after extraction; however, more refined high-performance liquid chromatography analysis showed that of three target compounds, the extract increased significantly with decreasing particle size. Additionally, ultra-micro pulverization exposes and releases compounds resulting in additional chemical components. Studies have found 21 compounds in QIG extract, including four phenolic acids, 15 gallotannins, and GA. Using different testing methods, the antioxidant and antibacterial properties of QIG have been confirmed. Baseline chemical composition has been identified to prevent adulteration or misuse in the future.

Pharmacological studies focused on the anti-inflammatory and antibacterial properties identified in QIG extracts and GA. In vitro studies have demonstrated the strong anti-inflammatory effects of QIG. In vivo oral and topical administration of QIG alcohol extracts have been shown to prevent the production of some inflammatory markers. Other studies have also confirmed its use as an anti-inflammatory.

Numerous studies showed beneficial uses of QIG as an antibacterial and antiviral. Both methanol and aqueous QIG extracts have demonstrated effectiveness against candida. Studies have also shown QIG to be effective against oral bacteria known to cause dental caries; thus, suggesting its use as an effective phytotherapeutic agent for the prevention of oral pathogens. Over-use of antimicrobials has led to multiple-drug-resistant strains of microbes. Several studies that QIG has the ability to kill pathogens and remove chronic drug-resistant infections.

Studies have shown GA has a significant inhibitory effect on tumor necrosis factor- a (TNF-a), interleukin-6 (IL-6), and histamine, which alleviate cell-induced inflammatory anaphylaxis. Showing promise in treating colorectal, pancreatic, lung, prostate, cervical, and skin cancer in vitro and in animal models, GA initiates apoptosis in tumor cells. It has also been shown to induce apoptosis in cells containing human papillomavirus. Low quantities of GA (< 25 µg mL-1) have been shown to enhance mitochondrial antioxidant capacity and increase cell proliferation following radiation damage. This same study showed that high concentrations of GA (> 25 µg mL-1) have the opposite effect. Both in vivo and in vitro studies have shown that GA protects DNA and cell membranes.

GA has been shown to have hepatoprotective benefits. It can act as a potential anti-fibrotic with an affinity for killing hepatic stellate cells, which are activated by liver injury and often lead to fibrosis. GA has also demonstrated the ability to regulate insulin secretion and inhibit the rate of a-amylase activity, indicating a metabolic effect. Finally, GA was demonstrated to have protective qualities for the nervous system. A moderate analgesic effect was demonstrated with QIG methanol extract using animal studies. QIG was shown in vivo and in vitro to protect against protozoan parasites. In vivo studies showed a positive effect on metabolism.

The authors conclude that QIG shows promise as a strong anti-inflammatory and antibacterial agent. While they present evidence of antitumor effects and other positive benefits on the human system, the authors strongly recommend that future studies are needed using human participants to study the mechanism of pharmacology, toxicology, and metabolism. Several studies did not clarify whether the test subjects were human. The authors imply that that article serves as a basis for future research on the application of medicinal plants. 

The authors declare no conflicts of interest.

Samaara Robbins